Modification of Hamburg Wheel-Tracking Test for Slow-Moving Heavy Traffic

The Hamburg wheel-tracking test (HWTT) is widely used to evaluate rutting resistance and moisture susceptibility of asphalt mixtures. While effective for standard traffic conditions, the test has shown limitations in predicting rutting potential under slow-moving heavy traffic at intersections or border checkpoints, leading to premature rutting problems and increased maintenance costs. This study proposed a modified HWTT at 70 °C to better address slow-moving heavy traffic conditions typically at intersections, based on pavement rutting development simulations, the time–temperature superposition principle, and laboratory and field evaluations. Laboratory evaluations using twenty asphalt mixtures with various aggregate types, binder grades, and binder sources demonstrated that the modified HWTT provides more discriminating assessments of rutting potential of asphalt mixtures. Preliminary field validation with cores from severely rutted intersections indicated that the modified HWTT at 70 °C can effectively identify rut-prone mixtures, whereas the standard HWTT at 50 °C does not. The modified HWTT offers a potential practical tool for designing rut-resistant asphalt mixtures tailored for intersections and other locations with slow-moving heavy traffic. While this study establishes an initial framework for addressing the rutting problem under slow-moving heavy traffic conditions, additional field validation across a wider range of materials, binder types, and climatic conditions is needed.